1. Field of the Invention
The invention is directed to an arrangement for an electronic manual postage meter machine (hand franking machine) with an ink-jet print head and with integrated means for controlling and supplying the ink-jet print head.
2. Description of the Prior Art
Postage meter machines of the above type can be employed everywhere where there is only low mail volume but there is a desire for a modern franking imprint.
The mechanical predecessor of such a postage meter machine is the D2 postage meter machine of Francotyp-Postalia that has been in use for many decades. This postage meter machine works without chip cards, so that the user must undertake a payment of fees at the post office, where a postal clerk directly sets the crediting system in the machine and seals it with a lead seal, as described in the instruction manual.
On the other hand, a franking tape generator system is known, as described in PCT Application WO 92/07338, with which a date a postage value and an advertizing slogan are printed on a franking tape. A printer unit, a processor system, a read-write means, an operating device and a tape supply container are arranged in a common housing. The write-read means serves the purpose of accepting postage credit cards and is connected to the processor system via information lines for the exchange of digitized data for identification, fee debiting and the individual advertizing slogan stored on the postage credit card. The digitized data of the advertizing slogan as well as monitoring and security data are likewise transmitted between the processor system and the printer unit via information and signal lines. The system can be operated independently of a network with batteries or rechargeable accumulators. For this system, the batteries must supply the energy for the printer unit as well as for the drive of the tape roll; accordingly, the batteries must be high-power batteries because the operating time would otherwise be limited. The tape supply container requires a corresponding volume. A loading of the postage meter machines at the post office is eliminated by employing postage credit cards, however, the franking tapes must be glued onto the postal matter and must be of such a nature that a re-use or further use is precluded.
A franker for printing a value imprint postal matter with an ink-jet printer means is also known, see German OS 27 01 072. The pattern of the postage value imprint is composed of successive sub-patterns. The franker contains an electronic control means for the ink-jet printer means and the control sequence thereof, a clock circuit for clocking the logic circuit during the course of printing as well as a postage fee memory. The franker is provided with a microcomputer operating on the basis of its own power supply whose clock circuit is actuated by a detector means. The detector means serves the purpose of identifying the relative speed of the franker with respect to the postal matter and supplying this information to the clock circuit as control signals. The clock circuit generates clock signals for the logic circuit of the microcomputer proportional to the relative speed. The ink-jet printer means successively emits the respective sub-patterns of the postage value imprint in the clock of these clock signals when the franker is moved over the postal matter. Two parallel axles each having two guide rollers at the ends serve to facilitate the motion. Eleven nozzles are arranged in the ink jet printer means in a row transverse relative to the moving direction of the franker.
The detector means is constructed as an optical monitor. A light source is the form of a light-emitting diode is focussed onto the region of the recording medium into which the ink drops are ejected from the ink jet printer means. The reflected light is supplied to a phototransistor via an optical probe composed of fibers. The microcomputer is programmed such that an ink drop is ejected every time the printer means is actuated. In order to permit a continuous optical scanning, a control pattern in the form of a line of printed dots is generated in addition to the actual franking imprint, the former underlining the latter. The monitor senses this line. The phototransistor reacts to changes from printing dot to free (unprinted) region in this control line and generates a pulsating signal that is forwarded to the microcomputer, the frequency of this pulsating signal thus being determined by the speed with which the monitor moves over the control line.
A rechargeable nickel-cadmium battery serves as the power supply.
Except for the nozzle discharge area, the housing of this known franker is closed with a cap that is displaceable corresponding to the stroke of an actuation switch but that can only be removed by an authorized person. This ensues in a postage distribution center when the stored postage has been largely used. The franker contains a number of input connections that are all accessible when the cap is removed. These input connections are composed of two sockets that are connected to the microcomputer, two sockets from the input of the power supply for the purpose of connection to a charging source, and a refill means for the ink reservoir.
After removal of the cap, the franker is plugged into a central location that has a main input plug that is connected to a charging means for the power supply, to an ink supply and a postage output computer. In one procedure, thus, the battery is recharged, additionally purchased postage is entered into the memory register of the microcomputer and the ink reservoir is filled.
It is obvious that the postage distribution center must usually be visited in order to recharge the battery, rather than for replenishing postage credit. If the hand franker is to meet moderns demands--printing not only a value imprint but an advertizing slogan as well--, then an ink printer head having 192 nozzles is required. Such an ink print head has a corresponding high energy consumption for setting the required operating temperature and for ink ejection which, if employed in a hand franker, would drain the battery long before the usual time for replenishing postage. Moreover, such ink print heads require an adapted cleaning mechanism that is entirely lacking in a hand franker. Since the nozzle area is always open, there is the risk during pauses in operation that the ink in the nozzle will dry and plug the nozzles. When the hand franker is mover over the postal matter on four parallel wheels running in the same direction, there is the risk that convexity and slippage arise in the recording medium and the print quality thus suffers. Determining the relative speed with bright-dark differences on the recording medium is susceptible to disruption dependent on the color of the recording medium, more so given a dark medium, less so given a light medium.
It has already been proposed in general for ink jet printers to attach an extraction means for cleaning the ink printer head to the latter itself, see German OS 27 25 761.
It has likewise been proposed for ink printers with a moving ink printer head that the nozzle discharge area be able to be covered in every position thereof, see German 29 19 727. To this end, a seal means that has a cover pad is moved together with the ink printer head on the basis of a mount. The seal means is displaceable from the outside in a position that makes the nozzle discharge area tight or releases it, this displacement occurring via a rocker extending over the entire range of motion of the ink printer head and via a coupling part placed against the mount. The nozzle area has a salient, all-around collar; the seal means is lowered thereinto. A cavity which is filled with ink by capillary action from the nozzles is formed in this way. This arrangement is specifically adapted to office printers, is relatively complex and the cleaning effect is achieved only with the cover cushion pad.
For intensifying the absorbency of an ink-absorbing means within a cap, another solution--see German OS 32 37 411--bring a suction line to the back side of the ink-absorbing means, an external suction pump being connected to the other end thereof. The ink stored in the absorbing means is eliminated in this way at the same time.
Finally, a ink jet recording device having at least one ink printer head and a regeneration means is also known from German OS 37 36 916.
In this device, a carriage with the ink printer heads is moved from a recording region into a regeneration and cleaning region. During the motion, the nozzle surface sweeps past an elastic wiper lip and is roughly cleaned in this way. A regeneration means having a cover housing is mounted against the ink printer head in the regeneration region, whereby each nozzle row, or each ink printer module given multi-color heads, is separately covered. The regeneration means operates with a suction pump. Ink, ink residues and air bubbles are suctioned off by under-pressure. This solution is also specifically tailored to an office printer.